1. Field of the Invention
This invention relates to a fuel metering control system for an internal combustion engine.
2. Description of the Related Art
The application of adaptive control theory to internal combustion engines in recent years has led to the development of technologies for adaptively controlling the actual quantity of fuel drawn into the engine cylinders to the desired fuel quantity, as taught, for example, by Japanese Laid-Open Patent Application No. Hei 1(1989)-110,853.
The present assignee's Japanese Patent Application No. Hei 4(1992)-215,665 (Japanese Laid-Open Patent Application No. Hei 6(1994)-42,385) (filed in the United States on Jul. 2, 1993 under the number Ser. No. 08/085,157) also teaches fuel metering control in an internal combustion engine using adaptive control. However, when actually applying the adaptive control to a fuel metering control, there are many problems to be solved so as to effectively conduct the control with high performance. More specifically, since the operating conditions of the engine ranging from a region in which combustion is stable to a region in which combustion is unstable, it is preferable to configure the system such that the control characteristics are easily determined in response to the region. In order to enlarge the marginal engine speed which allows the adaptive control to be conducted, moreover, it is preferable to decrease the volume or time of computation as low as possible.